Balthasar Hubmaier was the sort of chap who sometimes changed his mind depending on which way the wind was blowing that day. In the early years of the Reformation in Zurich he was an ally of Zwingli. Indeed, he was a staunch supporter. Then he started hanging out with the Re-Baptizers and he adopted their theology of baptism. When he was questioned by the Magistrates (after spending a few days in jail for his seemingly radical views) he changed his mind and turned against the Re-Baptizers. When he was then released from prison he left Zurich and again adopted the Re-Baptizers perspective.
Well, you get the point as to what kind of person he was.
By 1525 Hubmaier had written a little booklet on baptism which made the rounds pretty swiftly. Huldrych Zwingli responded on the 8th of November, 1525 with his Antwort über Balthasar Hubmaiers Taufbüchlein. In two parts, Zwingli examines Hubmaiers theology and responds to it. And in the second he offers a vigorous critique of re-baptism.